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<A NAME="pgfId-251760"></A>GROUP_DATA</H4>
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<A NAME="pgfId-251762"></A>The <A NAME="marker-251761"></A>GROUP_DATA policy applies to the <A NAME="marker-268403"></A>publisher and <A NAME="marker-268412"></A>subscriber entities via the <EM CLASS="Code">
group_data</EM>
 member of their respective QoS structures. Below is the IDL related to the group data QoS policy:</LI>
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<A NAME="pgfId-194643"></A><EM CLASS="Code">
</EM>
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<A NAME="pgfId-194687"></A><EM CLASS="Code">
struct GroupDataQosPolicy {</EM>
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<A NAME="pgfId-194591"></A><EM CLASS="Code">
  sequence&lt;octet&gt; value;</EM>
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<A NAME="pgfId-194565"></A><EM CLASS="Code">
};</EM>
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<A NAME="pgfId-194814"></A>&nbsp;</P>
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<A NAME="pgfId-195079"></A>By default, the <EM CLASS="Code">
value</EM>
 member is not set. It can be set to attach additional information to the created entities. The value of the GROUP_DATA policy is propagated via <A NAME="marker-268419"></A>built-in topics. The <A NAME="marker-268430"></A>data writer <A NAME="marker-268435"></A>built-in topic data contains the GROUP_DATA from the <A NAME="marker-268440"></A>publisher and the <A NAME="marker-268445"></A>data reader <A NAME="marker-268450"></A>built-in topic data contains the GROUP_DATA from the <A NAME="marker-268455"></A>subscriber. The GROUP_DATA policy could be used to implement matching mechanisms similar to those of the <A NAME="marker-199841"></A><a href="partition.html">PARTITION</a> policy except the decision could be made based on an application-defined policy.</LI>
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